Relationships between Tapetum, Loculus, and Pollen during Development

Abstract

Various parts of the anther (walls, tapetum, locular fluid, meiocytes, microspores) cooperate for correct pollen development. To show the different types of relationships possible between these parts, we considered the following characteristics, alone and in combination: types of tapetum, types of pollen‐dispersing unit, form of loculus, amount of locular space and fluid, number of pollen grains in transverse sections of the anther and in the loculus, and hydration status of pollen at dispersal. The different relationships between pollen, loculus, and tapetum should enable uniform nourishment of grains in the loculus and ensure a high percentage of viable grains. Two opposite modes were identified: direct and indirect nourishment of grains, the latter occurring when locular fluid is more or less abundant between the tapetum and the grains. The amount of space between developing grains determines different manners of grain nourishment and modes of pollen presentation for dispersal. Cyclosis, which is presu...